This invention relates to a heat sink for cooling a heat radiating body, more particularly to a heat sink, which has an excellent cooling efficiency and can effectively minimize the reduction of the cooling performance due to the alien substance such as dust.
For small current-consuming electronic devices such as transistors, integrated circuits, it is unnecessary to consider the heat radiation, since they radiate little heat. However, devices such as microprocessor used in computer system radiate heat considerably and so it increases the temperature of devices. Data processing speed and efficiency of the devices largely depend on how the heat energy generated in such devices can be controlled and removed efficiently. In case that the heat increases severely, the devices can be damaged permanently.
The most conventional heat sinks are pin-fin-type as shown in FIG. 1, and its base is formed of a good heat transmission material such as aluminum and there are tens to hundreds of heat radiating fins with shape as teeth of comb on the base to radiate heat generated from the processor, etc. The heat sink is mounted on the center of the chip package of the computer chip, and is attached to it using resin or clip, etc.
Since the heat sink does not have a good heat radiating efficiency in itself, fans are generally used additionally to enhance performance by generating air stream of cooling wind compulsorily and to contact the air stream to the fins, so that the heat is removed efficiently. Accordingly, heat generated in the heat-generating devices such as a microprocessor is transferred to the heat sink and absorbed into the cooling wind.
There have been many ways to contact the air stream generated by fan to fins in the conventional art. The most basic way is to blow the air stream of the cooling wind generated by the fan to the base perpendicularly, that is, from the upper part of the fin to lower part of it as shown in FIG. 1A. A problem in connection with this way is that since the air stream flows parallel to the fin from its upper part to its lower part, the thermal transmission coefficient of the sidewall of the fin becomes small and so the cooling efficiency is not good.
Another way is to blow the air stream of fan parallel to the base of the heat sink as shown FIG. 1B. A problem in connection with this way is that in the case the dimension of the heat sink becomes large and its length becomes long to the direction of the air stream, the pressure drop becomes large and the temperature of the air stream increases as the air stream flows along the lower part, so that the cooling effect on the lower part is not good.
To complement the above defects of conventional art, some heat sinks have been developed such as described in U.S. Pat. Nos. 5,063,476 and 5,083,194.
The heat sink described in U.S. Pat. No. 5,063,476 is a cooling system of so called air collision method (see FIG. 1C), where air stream inputted to the air intake inlet by a fan installed in the air discharge outlet is directed to the space between a fin 26 and another adjacent fin 26 by way of a nozzle. However, a problem in connection with the patent is that in case the area where air stream which has gone through the space among the fins 26 of the heat sink 24 and has contacted to the base is small, cooling performance also may drops. Moreover, it is also a problem that a space to install the nozzle has to be guaranteed in the heat sink.
U.S. Pat. No. 5,083,194 has a constitution where inflow air through the path between substrates collides with the heat sink 16 through nozzle 26 like U.S. Pat. No. 5,063,476. However, as shown in FIG. 1D, the above way has the same problem that air stream of the fan flows parallel to the fins as described in the conventional art.
Additionally, heat sinks which blow cooling wind between the porous media have a problem, i.e., as time passes, an alien substance such as dust becomes deposited among fins, therefore, it shortens the cooling performance of heat sink and lifetime of it.
Conventionally, since user seldom disassembles the apparatus and cleanses the dust deposited in the heat sink, it is not possible to cleanse automatically the alien substance, once deposited in the heat sink.
An object of the present invention is to solve the problems of the conventional art such as law-efficiency of cooling performance and deposition of alien substance, and to provide a heat sink with excellent cooling efficiency.
Unlike the conventional method where cool air stream is provided parallel or perpendicularly to the pin fin, the present invention solves the problems by providing cool air stream to the heat sink with a slope to the pin fin.
These and other objects of the present invention are achieved through a first embodiment of the heat sink, which includes a rectangular parallel-piped body whose bottom plate is attached to the surface of a heat-generating device; upper-lower parts separating plate to separate the inner part of the rectangular parallel-piped body into upper and lower parts; side part separating plates formed between the bottom plate and the upper-lower parts separating plate with a slope to separate the lower space formed by the upper-lower parts separating plates into a plurality of sections; nozzle parts inserted in the middle of the side part separating plates with a slope to its attachment surface; a plurality of pin-type fins formed in the bottom surface of a plurality of sections separated by the upper-lower parts separating plates; and air stream transportation means installed on the upper space formed by the upper-lower parts separating plates and supplying cooling air stream to the fins through the nozzle parts.
These and other objects of the present invention are achieved through a second embodiment of the heat sink, which includes a rectangular parallel piped body whose bottom plate is attached to heat-generating surface of the heat-generating device; side part separating plates formed between the bottom plate and ceiling plate with a slope to separating the inner part of the rectangular parallel piped body; nozzle parts inserted in the middle of the side part separating plates with a slope to its attachment surface; a plurality of pin-type fins formed in the bottom surface of a plurality of sections separated by the side part separating plates; and air stream transportation means installed on the most end section among a plurality of sections and supplying cooling air stream to the fins through the nozzle parts.
Preferably, the slope of the side part separating plates to the base part may be in the range of 15 degree to 45 degree.
Preferably, the air stream transportation means may be a fan or a blower.
Preferably, the fan inflows air stream from the outer part of the heat sink or flows out air stream from the inner part of the heat sink.
Preferably, the outlet area of a nozzle is narrower than the inlet area of it.